How do I set a velocity for a Kanban team?

[Lawrence Leonard]

In portfolio, the team velocity appears greyed out and is not editable. It appears that I may not have proper access rights to change that.  What access rights do I need?  How can I see my access rights and how can I change them?  My IT group figured it out.  Click on the non-editable velocity.  Go to "Past Velocity".  Select "Use suggested velocity".  The velocity will be updated to a 5 sprint average and now be editable.

An Atlassian article, https://www.atlassian.com/blog/jira-software/kanban-with-portfolio-for-jira, suggests using throughput over a period of time to establish a velocity for a kanban team.  The problem is since a kanban team never establishes a velocity in Jira, the approach above for making the velocity editable does not work.  Is there another way to make the velocity field editable?  Is there a way to establish a Kanban velocity in Jira?

Thanks